Detection: Detect New Local Admin account

Updated Date: 2024-05-15 ID: b25f6f62-0712-43c1-b203-083231ffd97d Author: David Dorsey, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the creation of new accounts elevated to local administrators. It uses Windows event logs, specifically EventCode 4720 (user account creation) and EventCode 4732 (user added to Administrators group). This activity is significant as it indicates potential unauthorized privilege escalation, which is critical for SOC monitoring. If confirmed malicious, this could allow attackers to gain administrative access, leading to unauthorized data access, system modifications, and disruption of services. Immediate investigation is required to mitigate risks and prevent further unauthorized actions.

1`wineventlog_security` EventCode=4720 OR (EventCode=4732 Group_Name=Administrators) 
2| transaction src_user connected=false maxspan=180m 
3| rename src_user as user 
4| stats count min(_time) as firstTime max(_time) as lastTime by user dest 
5| `security_content_ctime(firstTime)` 
6| `security_content_ctime(lastTime)` 
7| `detect_new_local_admin_account_filter`

Data Source

Name Platform Sourcetype Source Supported App
Windows Event Log Security 4720 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Security' N/A

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
detect_new_local_admin_account_filter search *
detect_new_local_admin_account_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1136.001 Local Account Persistence
T1136 Create Account Persistence
KillChainPhase.INSTALLATION
NistCategory.DE_CM
Cis18Value.CIS_10
APT3
APT39
APT41
APT5
Dragonfly
FIN13
Fox Kitten
Kimsuky
Leafminer
Magic Hound
TeamTNT
Wizard Spider
Indrik Spider
Scattered Spider

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting Value
Disabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Creates Notable Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Risk Event True
This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

You must be ingesting Windows event logs using the Splunk Windows TA and collecting event code 4720 and 4732

Known False Positives

The activity may be legitimate. For this reason, it's best to verify the account with an administrator and ask whether there was a valid service request for the account creation. If your local administrator group name is not "Administrators", this search may generate an excessive number of false positives

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
A $user$ on $dest$ was added recently. Identify if this was legitimate behavior or not. 42 60 70
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset WinEventLog:Security WinEventLog
Integration ✅ Passing Dataset WinEventLog:Security WinEventLog

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 4